Total hemoglobin screening sensor

ABSTRACT

A total hemoglobin index system derives total hemoglobin (tHb) index value utilizing a depopulated emitter with an index set of LEDs. A patient fails a tHb index test if tHb measurements are trending down and/or tHb values fall below a predefined index threshold. If a patient fails the tHb index test, a high resolution sensor derives a specific tHb measurement utilizing a high resolution set of LEDs. The number of high resolution set LEDs is greater than the number of index set LEDs.

PRIORITY CLAIM TO RELATED PROVISIONAL APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 14/845,090, filed Sep. 3, 2015, titled Total HemoglobinScreening Sensor, which claims priority benefit under 35 U.S.C. § 119(e)to U.S. Provisional Patent Application Ser. No. 62/045,565 filed Sep. 4,2014, titled Total Hemoglobin Screening Sensor, hereby incorporated inits entirety by reference herein.

BACKGROUND OF THE INVENTION

Pulse oximetry systems for measuring constituents of circulating bloodhave gained rapid acceptance in a wide variety of medical applications,including surgical wards, intensive care and neonatal units, generalwards, home care, physical training, and virtually all types ofmonitoring scenarios. A pulse oximetry system generally includes anoptical sensor applied to a patient, a monitor for processing sensorsignals and displaying results and a patient cable electricallyinterconnecting the sensor and the monitor. A pulse oximetry sensor haslight emitting diodes (LEDs), typically one emitting a red wavelengthand one emitting an infrared (IR) wavelength, and a photodiode detector.The emitters and detector are attached to a patient tissue site, such asa finger. The patient cable transmits drive signals to these emittersfrom the monitor, and the emitters respond to the drive signals totransmit light into the tissue site. The detector generates a signalresponsive to the emitted light after attenuation by pulsatile bloodflow within the tissue site. The patient cable transmits the detectorsignal to the monitor, which processes the signal to provide a numericalreadout of physiological parameters such as oxygen saturation (SpO₂) andpulse rate. Advanced physiological monitoring systems utilize multiplewavelength sensors and multiple parameter monitors to provide enhancedmeasurement capabilities including, for example, the measurement ofcarboxyhemoglobin (HbCO), methemoglobin (HbMet) and total hemoglobin(tHb).

Pulse oximeters capable of reading through motion induced noise aredisclosed in at least U.S. Pat. Nos. 6,770,028, 6,658,276, 6,650,917,6,157,850, 6,002,952, 5,769,785, and 5,758,644; low noise pulse oximetrysensors are disclosed in at least U.S. Pat. Nos. 6,088,607 and5,782,757; all of which are assigned to Masimo Corporation, Irvine,Calif. (“Masimo”) and are incorporated in their entireties by referenceherein.

Physiological monitors and corresponding multiple wavelength opticalsensors are described in at least U.S. patent application Ser. No.11/367,013, filed Mar. 1, 2006 and entitled Multiple Wavelength SensorEmitters and U.S. patent application Ser. No. 11/366,208, filed Mar. 1,2006 and entitled Noninvasive Multi-Parameter Patient Monitor, bothassigned to Cercacor Laboratories, Irvine, Calif. (Cercacor) and bothincorporated in their entireties by reference herein.

Further, physiological monitoring systems that include low noise opticalsensors and pulse oximetry monitors, such as any of LNOP® adhesive orreusable sensors, SofTouch™ sensors, Hi-Fi Trauma™ or Blue™ sensors; andany of Radical®, SatShare™, Rad-9™, Rad-5™, Rad-5v™ or PPO+™ Masimo SET®pulse oximeters, are all available from Masimo. Physiological monitoringsystems including multiple wavelength sensors and correspondingnoninvasive blood parameter monitors, such as Rainbow™ adhesive andreusable sensors and RAD-57™ and Radical-7™ monitors for measuring SpO₂,pulse rate, perfusion index, signal quality, HbCO and HbMet among otherparameters are also available from Masimo.

SUMMARY OF THE INVENTION

Occult bleeding is frequent in surgery, intensive care and obstetrics,and late detection increases the corresponding risks of serious injuryor death. Bleeding alone is responsible for 19% of in-hospital maternaldeaths. Further, bleeding significantly increases the total cost ofpatient treatment. Total hemoglobin (tHb) measurements identify almost90% of patients with bleeding, but traditional lab measurements areinfrequent and delayed. Advantageously, a tHb index system is an aid toclinicians in intensive care units and labor and delivery wards todetect occult bleeding.

Traditional invasive lab testing provides delayed results and requires apainful needle stick and time-consuming blood draws. A total hemoglobin(tHb) index system incorporating an advantageous noninvasive, disposablesensor and a monitor advantageously calculating and displaying a tHbindex facilitates timely patient assessment and reduces the need to waitfor lab results.

Also, noninvasive tHb monitoring advantageously provides real-timevisibility to changes, or lack of changes, in total hemoglobin betweeninvasive blood sampling. Continuous, real-time tHb monitoring isparticularly advantageous when a tHb trend is stable and a clinician mayotherwise think tHb is dropping; a tHb trend is rising and the clinicianmay otherwise think tHb is not rising fast enough; or the tHb trend isdropping and the clinician may otherwise think tHb is stable.

Further, a tHb index system decreases the risk of accidental needlesticks and exposure to blood-borne pathogens. In addition, a disposabletHb sensor requires no lab consumables or waste disposal, reducespainful needle sticks and time-consuming blood draws and enablesimmediate face-to-face counseling with a clinician. The advantages of atHb index system are enhanced through the use of a low-cost tHb indexsensor embodiment utilizing a reduced number of LEDs in the emitter, asdescribed below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a total hemoglobin index system including a totalhemoglobin (tHb) index monitor and a corresponding disposable tHb indexoptical sensor responsive to pulsatile blood flow within a fingertip;

FIG. 2 is a general flow diagram of tHb index monitoring utilizing acombination of optical sensors including an index sensor and ahigh-resolution sensor;

FIGS. 3A-B are a tHb index sensor characterization flow diagram and acorresponding sensor characterization graph;

FIGS. 4A-B are a tHb high-resolution sensor characterization flowdiagram and corresponding sensor characterization graph;

FIG. 5 is a detailed flow diagram of tHb testing utilizing a combinationof index and high-resolution disposable optical sensors;

FIG. 6 is a handheld-monitor tHb index display;

FIG. 7 is a multi-parameter monitor display illustrating a tHb index inconjunction with various other pulsatile blood flow parameters;

FIGS. 8A-B are perspective and top views, respectively, of a tHb indexsensor;

FIGS. 9A-E are top and bottom head tape assembly views, enlargeddetector window and emitter window views and a connector schematic view,respectively, of a tHb index sensor.

FIG. 10 is an exploded view of a tHb index sensor;

FIGS. 11A-D are top, top-perspective, side and bottom-perspective views,respectively, of a tHb sensor emitter assembly;

FIGS. 12A-D are top, top-perspective, side and bottom-perspective views,respectively, of a tHb sensor detector assembly;

FIGS. 13A-B are LED layout and corresponding emitter schematic views ofan emitter assembly; and

FIGS. 14A-B are a socket and plug perspective view and a socket and plugperspective cutaway view of a pogo pin connector assembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates a total hemoglobin (tHb) index system 100 including astandalone monitor 101, a portable handheld monitor 120 and a disposableoptical sensor 800. The standalone monitor 101 has a main display 700and the removable handheld monitor 120 has a handheld display 600. Theoptical sensor 800 attaches to a fingertip 1 so as to optically analyzeblood constituents therein, including tHb and others described withrespect to FIG. 7, below. In a particular embodiment, the sensor 800 hasemitters (LEDs) capable of irradiating the tissue site 1 with multiplewavelengths of light and corresponding detectors capable of detectingthe light after attenuation by pulsatile blood flow within the tissuesite 1. The sensor 800 removably connects to a patient cable 130, whichconnects to the monitor 101. In particular, the patient cable 130 has asensor-side connector 132 that removably attaches to and electricallycommunicates with the sensor connector 810 and a monitor-side connector134 that removably attaches to and electrically communicates with thehandheld monitor via a handheld connector 124. The handheld monitor 120has a monitor mount connector (not visible) that allows the sensor 800to communicate with the monitor 101. Blood parameter measurementsresponsive to the index sensor 800 are displayed on the handheld display600 and/or the larger monitor display 700. A patient monitoring platformresponsive to optical sensors among others and providing both handheldand standalone monitoring capabilities is available from MasimoCorporation, Irvine, Calif.

As shown in FIG. 1, an optical sensor 800 disposed of after a singlepatient use is relatively expensive. Reducing the number of sensoremitters may significantly reduce the cost of testing patients for someconditions, such as blood-loss. In an advantageous embodiment, at leasttwo sensors are provided for medical use. A relatively inexpensive“index sensor” has a reduced set of emitters (fewer wavelengths) andmeasures a blood parameter, such as tHb, with a correspondingly lowerresolution. A relatively expensive high resolution or “hi-res” sensorhas an expanded set of emitters (more wavelengths) and measures bloodparameters with greater accuracy. In an advantageous embodiment,described in further detail with respect to FIGS. 2-14 below, a totalhemoglobin index system derives a unit-less tHb index that varies overtime. A tHb index advantageously utilizes a less expensive index sensorwith a minimal number of LED emitters so as to reduce disposable sensorcosts during initial patient testing.

FIG. 2 illustrates total hemoglobin (tHb) index monitoring 200 thatadvantageously uses a fewer-LED (index) sensor 210 for an initial tHbtest. A high resolution (hi-res) sensor 230 that uses more-LEDs is usedonly if tHb issues, such as potential internal bleeding, cannot beeliminated by the index sensor 210. Both the index sensor 210 and thehi-res sensor 230 are single-use, disposable sensors. The hi-res sensor230 is substantially more expensive than the index sensor 250 due to LEDcosts. In a particular embodiment, the index sensor 210 uses four LEDsand the high-res sensor uses eight LEDs. A tHb index sensor embodimentis described in detail with respect to FIGS. 8-14, below. A hi-ressensor is described with respect to U.S. patent application Ser. No.12/056,179 filed Mar. 26, 2008, titled Multiple Wavelength OpticalSensor, assigned to Masimo Corporation, Irvine, Calif. and incorporatedin its entirety by reference herein.

As shown in FIG. 2, a total hemoglobin (tHb) index 200 embodiment beginswith a tHb measurement request 201 initially fulfilled with a tHb indexsensor 210. The relatively low cost, low resolution index sensor isadvantageously utilized to derive a dimensionless trend 211. Forexample, a stable trend over a sufficiently long period of time may besufficient assurance to a care provider that further testing isunnecessary, as described with respect to FIG. 3, below. DimensionlesstHb trend displays are described with respect to FIGS. 6-7, below.

Also shown in FIG. 2, if a tHb trend is inconclusive 212, a careprovider may request a high-resolution sensor 230. If noninvasivemeasures fail to yield a definitive diagnosis, an invasive blood draw260 and corresponding laboratory analysis is utilized alone or inaddition to continuous high resolution sensor measurements for adefinitive tHb assessment. Appropriate patient therapy 252 may includefollow-up surgery and blood transfusion.

FIGS. 3A-B illustrate a tHb index sensor method including acharacterization flow diagram 301 and a corresponding sensorcharacterization graph 302. As shown in FIG. 3A, astatistically-significant population of index tHb sensors 310 ischaracterized 330 by measuring the mean (pi) and standard deviation (σ₁)of a Gaussian-distributed population of tHb measurements. Thecorresponding z score of the index sensors 350 is calculated as:

$\begin{matrix}{Z = \frac{x - \mu_{1}}{\sigma_{1}}} & {{EQ}.\mspace{14mu} 1}\end{matrix}$

As shown in FIG. 3B, the probability that a tHb measurement for a givenindex sensor is less than z is the shaded area 370 of a normaldistribution having a mean pi and a standard deviation σ₁. For example,from a standard statistical table, a z value of 1.28 indicates a 89.97%(˜90%) probability that the measured value is less than z. Use of aindex sensor z value for initial tHb index 210 (FIG. 2) is described infurther detail with respect to FIG. 5, below.

FIGS. 4A-B illustrate a high-resolution tHb sensor characterizationmethod including a characterization flow diagram 401 and a correspondingsensor characterization graph 402. As shown in FIG. 4A, astatistically-significant population of high-resolution tHb sensors 410is characterized 430 by measuring the mean (μ₂) and standard deviation(σ₂) of a Gaussian-distributed population of tHb measurements. Thecorresponding accuracy of the high-resolution sensor is calculated as:

tHb=μ ₂±σ₂  EQ. 2

As shown in FIG. 4B, the probability that a tHb measurement for a givenhigh-resolution sensor is within one standard deviation of the mean is68%. Use of a high-resolution sensor tHb measurement is described infurther detail with respect to FIG. 5, below.

FIG. 5 further illustrates tHb testing 500 utilizing a combination of adisposable index sensor and a disposable high-resolution sensor.Initially, a disposable tHb index sensor is attached to a patient and acorresponding monitor 101 (FIG. 1). The monitor reads the index sensor510 to obtain a total hemoglobin estimate

. That estimate is compared with the z-value 520, as described withrespect to EQ. 1, above. If the total hemoglobin estimate is greaterthan z, then the patient has a sufficiently high tHb to pass the test522, i.e. to eliminate low tHb and issues regarding low tHb (such asinternal bleeding) as a concern. In an embodiment, z is chosen so thatthe probability that tHb is too low is approximately 90%.Advantageously, use of a relatively inexpensive, minimallyemitter-populated index sensor at this stage of patient testing providesa significant cost-saving over time and encourages more frequent use ofnoninvasive tHb testing as a patient care standard.

Further shown in FIG. 5, in the event

is less than z 524 then tHb is retested utilizing a disposable highresolution sensor 530. If tHb is greater than tHb_(min), then thepatient has a sufficiently high tHb to pass the test 542.Advantageously, even though a second, more expensive fullyemitter-populated high-resolution sensor is used during this secondstage test, this multistage test is configured to have an overall costsavings as compared to solely using high-resolution sensors. Although anindex sensor test described above is based upon a z-value, other tHbthreshold measures may be used. As an example, a fraction of ormultiplier of z may be used to calculate the index sensor threshold.

Traditional invasive lab testing provides delayed results and requires apainful needle stick and time-consuming blood draws. A total hemoglobin(tHb) index system incorporating an advantageous noninvasive, disposablesensor and a monitor advantageously calculating and displaying a tHbindex facilitates timely patient assessment and reduces the need to waitfor lab results.

Also, noninvasive tHb monitoring advantageously provides real-timevisibility to changes, or lack of changes, in total hemoglobin betweeninvasive blood sampling. Continuous, real-time tHb monitoring isparticularly advantageous when a tHb trend is stable and a clinician mayotherwise think tHb is dropping; a tHb trend is rising and the clinicianmay otherwise think tHb is not rising fast enough; or the tHb trend isdropping and the clinician may otherwise think tHb is stable.

FIGS. 6-7 illustrate advantageous graphical index measures of totalhemoglobin (tHb index) that address the need to provide real-timevisibility to changes while using a relatively inexpensive tHb indexsensor. FIG. 6 illustrates a tHb index display 600 embodimentadvantageously suited for a relatively small area display, such as on ahandheld monitor 120 (FIG. 1). In particular, the handheld tHb index hasno time axis. Instead, a vertical bar graph 610 has dimensionless green612, yellow 614 and red 616 zones for indicating a range of relative tHbvalues. The present relative value of a tHb index is indicated by avertical-ranging pointer 620 and a dotted line 640 extendinghorizontally across the display 600. A horizontal line 660 is disposedacross the width of the display between the green zone 612 and yellowzone 614. A tHb value 650 is listed at the display bottom, e.g. “10.5g/dL @ 90% C.I.” Accordingly, the horizontal line 660 represents 10.5g/dl and a corresponding 90% confidence interval that the present tHbvalue is greater than 10.5 g/dL. In this example, the yellow zone 614represents a 10% likelihood the present tHb value is less than 10.5g/dL. Although the tHb index display has no time axis, a trend indicator630 has up arrow, horizontal line and down arrow symbols. The currenttHb index trend is indicated by a highlighted one of these symbols.

FIG. 7 illustrates a multi-parameter monitor display 700 including suchparameters as oxygen saturation, pulse rate, respiration rate, tHb index710, pulse variability index (PVI), perfusion index (PI) and oxygencontent (SpOC) versus time. An advantageous tHb index versus timedisplay 710 has no listed parameter range 740. However, a baseline tHbvalue 720 is displayed as a horizontal line and a time varying tHb index730 is displayed relative to the baseline 720. The baseline 720 is setat a tHb value and corresponding confidence interval, as described withrespect to FIG. 6, above.

FIGS. 8A-B generally illustrate a disposable index sensor 800 thatremovably attaches to a fingertip and electrically interconnects to aphysiological monitor as shown and described with respect to FIG. 1,above. The sensor 800 has an adhesive butterfly wrap 810, a headassembly 900 and a release liner 840. The head assembly 900 has a sensorhead 910, a connector 930 and an insulated interconnect 920. Theinterconnect 920 provides mechanical and electrical communicationsbetween the sensor head 910 and the connector 930. The release liner 840is removed from the adhesive butterfly wrap 810 so as to attach thesensor head 910 to a fingertip 1 (FIG. 1). A connector 930 inserts intoa corresponding patient cable socket 132 (FIG. 1) so as to providecommunications between the sensor 800 and a standalone monitor 101(FIG. 1) or portable handheld monitor 120 (FIG. 1).

FIGS. 9A-E further illustrate the head tape assembly 900 including afirst head tape side (FIG. 9A), a second head tape side (FIG. 9B), adetector window 912 (FIG. 9C) exposing the detector 1200, an emitterwindow 914 (FIG. 9D) exposing the emitter 1100 and a connector 935 (FIG.9E) schematic view, respectively, for a tHb index sensor. As shown inFIG. 9A, the first head tape side has an imprinted fingernail target 906on a bottom half 905. As shown in FIG. 9B, the second head tape side hasan imprinted finger pad target 909 on a top half 908 and a printed foldline 907 separating the top half 908 and bottom half 905. The sensorhead 910 (FIGS. 8A-B) is attached to a fingertip site by placing thefingernail target 906 over a fingernail, folding the sensor head at thefold line 907 and over the fingertip so as to place the finger padtarget on a finger pad. The sensor head 910 is then held in place byfolding the butterfly wrap 810 (FIGS. 8A-B) around the finger 800 (FIG.1).

As shown in FIG. 9E, the connector 930 (FIG. 9A) and in particular, theconnector contacts 935 allow a monitor to sequentially activate the LEDs1100, which illuminate a fingertip with red and IR wavelengths. Thedetector 1200 is responsive to the wavelengths after attenuation bypulsatile blood flow within the fingertip. The monitor analyzes thedetector signal so as to measure blood constituents including tHb. Themonitor may also read an EEPROM 990 and resistor 970 mounted in theconnector 930 so as to identify the sensor 800 (FIGS. 8A-B).

FIG. 10 further illustrates the tHb index sensor described above withrespect to FIGS. 8-9. The tHb index sensor 1000 (800 FIGS. 8A-B) has anadhesive butterfly wrap 810, a top head tape 1070, a polyethylene foamtape insulator 1040, 1060, a flex circuit assembly 1050, a bottom headtape 1080 and a release liner 840. The sensor connector 930 has an LEDlabel 1010 identifying this as a index sensor, a connector top shell1020, a sensor bottom shell 1030 and adhesives 1092, 1094.

FIGS. 11-13 illustrate in detail the optical elements of a tHb indexsensor 800 (FIGS. 8A-B), including an emitter 1100 that sequentiallyilluminates a fleshy tissue site, such as a fingertip, with fourdiscrete wavelengths of optical radiation and a detector 1200 that isresponsive to the optical radiation after absorption by pulsatile bloodflow within the tissue site. A monitor 100 (FIG. 1) has processorsresponsive to the detector 1200 so as to derive an indication of one ormore blood constituents, such as a tHb trend described with respect toFIGS. 6-7 above.

As shown in FIGS. 11A-D, an emitter 1100 has an encapsulant 1110 housinga lead frame 1120 and emitter dice 1130 mounted and wire bonded to thelead frame 1120. As shown in FIGS. 12A-D, a detector 1200 has anencapsulant 1210 housing a lead frame 1220 and a detector die 1230mounted and wire bonded to the lead frame 1220. The emitter 1100 anddetector 1200 are mounted via their respective lead frames 1120, 1220 toa flex circuit assembly 1050 (FIG. 10), as described above, so as torespond to emitter drive signals from a monitor via a connector 935(FIG. 9E) and to transmit detector signals to a monitor via theconnector 935 (FIG. 9E).

As shown in FIGS. 13A-B, in a 4-wavelength embodiment, LEDs are mountedon a lead frame 1301 having three leads 1320, 1330, 1340. Four LED die1311-1314 are each mounted on one face and wire bonded on an oppositeface to various lead frame pads RIC1, R2C2, R3C3 proximate an emitteroptical center 1350. In a particular embodiment, the LEDs emit light at660 nm, 905 nm, 1170 nm and 1300 nm.

FIGS. 14A-B illustrate a pogo pin sensor connector assembly. As shown inFIG. 14A, the connector assembly 1400 has a plug 1410 that accepts flexcircuit conductors via a generally elongated aperture 1412 and a socket1420 that accepts cable conductors via a generally round aperture 1422.A plug shelf 1450 provides a generally solid, flat surface for fixedlymounting flex circuit connector pads e.g. 935 (FIG. 9A), which areinserted into the socket 1420. The plug 1410 provides a sensor connectore.g. 810 (FIG. 1) and the socket 1420 provides a monitor cable connector132 (FIG. 1) so as to allow a monitor and sensor to electricallycommunicate drive signals and sensor signals as described above.

As shown in FIG. 14B, when the plug 1410 is fully inserted into thesocket 1420, a plug latch 1440 engages a socket catch 1430 removablysecuring the plug 1410 to the socket 1420. Spring-mounted pogo pins 1470in the socket 1420 mechanically and electrically engage flex circuitpads on the plug 1410 so as to electrically interconnect flex circuitand cable conductors. A release 1460 disengages the catch 1430 and latch1440 allowing the plug 1410 to be removed from the socket 1420.

A total hemoglobin index system has been disclosed in detail inconnection with various embodiments. These embodiments are disclosed byway of examples only and are not to be construed as limiting the scopeof the claims that follow. One of ordinary skill in art will appreciatemany variations and modifications.

1-17. (canceled)
 18. A physiological monitoring system for measuringtotal hemoglobin in a patient comprising: a first optical sensorconfigured to measure a first total hemoglobin estimate, the firstoptical sensor including: a first plurality of emitters configured toemit optical radiation comprising one or more wavelengths towards tissueat a tissue measurement site when the first optical sensor is in use,wherein pulsatile blood flows through the tissue of the patient at thetissue measurement site; a first detector configured to detect theoptical radiation emitted from the first plurality of emitters afterattenuation by the pulsatile blood flowing through the tissue at thetissue measurement site when the first optical sensor is in use, thefirst detector further configured to output a first signal responsive tothe detected, attenuated light after being emitted by the firstplurality of emitters; a second optical sensor configured to measure asecond total hemoglobin estimate, the second optical sensor including: asecond plurality of emitters configured to emit optical radiationcomprising one or more wavelengths towards the tissue at the tissuemeasurement site when the second optical sensor is in use; and a seconddetector configured to detect the optical radiation emitted from thesecond plurality of emitters after attenuation by the pulsatile bloodflowing through the tissue at the tissue measurement site when thesecond optical sensor is in use, the second detector further configuredto output a second signal responsive to the detected, attenuated lightafter being emitted by the second plurality of emitters; wherein thesecond plurality of emitters of the second optical sensor comprises moreemitters than the first plurality of emitters in the first opticalsensor; a physiological monitor configured to communicate with the firstoptical sensor and the second optical sensor and receive at least one ofthe first signal responsive from the first optical sensor and the secondsignal from the second optical sensor, the physiological monitor furtherconfigured to provide an indication to measure the second totalhemoglobin estimate with the second optical sensor if the first totalhemoglobin estimate is below a predetermined threshold.
 19. The systemaccording to claim 18, wherein the first plurality of emitters of thefirst optical sensor comprise four LEDs and the second plurality ofemitters of the second optical sensor comprise eight LEDs.
 20. Thesystem according to claim 19, wherein each of the four LEDs of the firstoptical sensor comprises a different wavelength selected from the groupconsisting of 660 nm, 905 nm, 1170 nm, and 1300 nm.
 21. The systemaccording to claim 18, wherein at least one of the first optical sensorand the second optical sensor comprise a sensor connector in electricalcommunications with the physiological monitor.
 22. The system accordingto claim 18, wherein the tissue measurement site is located on a fingerof the patient.
 23. The system according to claim 22, wherein at leastone of the first optical sensor and the second optical sensor comprisean adhesive butterfly wrap configured to secure to the finger of thepatient when in use.
 24. The system of claim 18, wherein thephysiological monitor is further configured to generate a totalhemoglobin index display comprising the first total hemoglobin estimate.25. The system of claim 24, wherein the total hemoglobin index displayof the physiological monitor has no time axis and comprises a verticalbar graph for indicating a range of relative total hemoglobin values.26. The system of claim 25, wherein the total hemoglobin index displayfurther comprises a pointer configured to move vertically so as toindicate a present total hemoglobin index value.
 27. The system of claim26, wherein the total hemoglobin index display further comprises a trendindicator.
 28. A method for measuring total hemoglobin in a patient, themethod comprising: attaching a first optical sensor to the patient, thefirst optical sensor configured to measure a constituent of thepatient's blood, the first optical sensor comprising: a first pluralityof emitters configured to emit optical radiation comprising one or morewavelengths towards tissue at a tissue measurement site, whereinpulsatile blood flows through the tissue of the patient at the tissuemeasurement site; and a first detector configured to detect the opticalradiation emitted from the first plurality of emitters after attenuationby the pulsatile blood flowing through the tissue at the tissuemeasurement site, the first detector further configured to output afirst signal responsive to the detected, attenuated light after beingemitted by the first plurality of emitters; measuring a first totalhemoglobin estimate using the first optical sensor; and if the firsttotal hemoglobin estimate is below a predetermined threshold, replacingthe first optical sensor with a second optical sensor and measuring asecond total hemoglobin estimate with the second optical sensor, whereinthe second optical sensor comprises: a second plurality of emittersconfigured to emit optical radiation comprising one or more wavelengthstowards the tissue at the tissue measurement site; and a second detectorconfigured to detect the optical radiation emitted from the secondplurality of emitters after attenuation by the pulsatile blood flowingthrough the tissue at the tissue measurement site, the second detectorfurther configured to output a second signal responsive to the detected,attenuated light after being emitted by the second plurality ofemitters, the second plurality of emitters comprising more emitters thanthe first plurality of emitters in the first optical sensor.
 29. Themethod according to claim 28, wherein measuring the first totalhemoglobin estimate further comprises transmitting the first signal ofthe first optical sensor to a physiological monitor.
 30. The method ofclaim 29, wherein at least one of the first optical sensor and thesecond optical sensor comprise a sensor connector in electricalcommunications with the physiological monitor.
 31. The method accordingto claim 29, further comprising: analyzing the first signal to determinea total hemoglobin trend; and graphically showing the total hemoglobintrend on a display of the physiological monitor.
 32. The method of claim31, wherein the display of the physiological monitor has no time axisand comprises a vertical bar graph for indicating a range of relativetotal hemoglobin values.
 33. The method of claim 32, wherein the displayfurther comprises a pointer configured to move vertically so as toindicate a present total hemoglobin index value.
 34. The method of claim28, wherein the first plurality of emitters of the first optical sensorcomprise four LEDs and the second plurality of emitters of the secondoptical sensor comprise eight LEDs.
 35. The method of claim 28, whereinthe tissue measurement site is located on a finger of the patient. 36.The method of claim 35, wherein at least one of the first optical sensorand the second optical sensor comprise an adhesive butterfly wrapconfigured to secure to the finger of the patient when in use.
 37. Themethod of claim 28, wherein measuring the first total hemoglobinestimate comprises sequentially transmitting 660 nm, 905 nm, 1170 nm,and 1300 nm wavelengths from the first optical sensor into a fingernailportion of the tissue measurement site.